1. Field of the Invention
The present invention relates to a charging member which is used in an electrophotographic apparatus, a process cartridge, and the electrophotographic apparatus.
2. Description of the Related Art
In an electrophotographic apparatus, a charging member (hereinafter also referred to as a “charging roller”) which comes into contact with the surface of an electrophotographic photosensitive member and has a roller shape for charging the surface of the electrophotographic photosensitive member generally has an elastic layer containing a resin. Such a charging roller can sufficiently secure a nip width between the charging roller and the electrophotographic photosensitive member, and as a result, can efficiently and uniformly charge the electrophotographic photosensitive member. However, the elastic layer contains a low-molecular-weight component of a plasticizer or a resin, so as to be softened. Therefore, the low-molecular-weight component may bleed to the surface of the charging roller after long-term use. With respect to such a problem, Japanese Patent Application Laid-Open No. 2001-173641 discloses a conductive roll substrate which covers the surface of the charging roller with a bleeding block layer consisting of an inorganic oxide film formed by a sol-gel method, and suppresses the bleeding of the low-molecular-weight component up to the surface.